Register buffers with an execution context.
template< typename ExecutionContext, typename MutableBufferSequence, typename Allocator> buffer_registration< MutableBufferSequence, Allocator > register_buffers( ExecutionContext & ctx, const MutableBufferSequence & buffer_sequence, const Allocator & alloc, typename constraint< is_convertible< ExecutionContext &, execution_context & >::value >::type = 0);